Alteration of glycan structures by swainsonine affects steroidogenesis in bovine luteal cells

Some phytotoxins causing reproductive alterations in ruminants

The presence of phytotoxins in plants constitutes a health risk for herbivores, particularly on ruminants who accidently consume them. Among the adverse effects produced by these are reproductive alterations, represented by abortion, infertility, and morphological alterations in neonates, which are frequently attributed to other causes. While in some cases the plants that contain such metabolites are known, other times they are not, leading to alterations that are difficult to treat considering that their toxicodynamics are unknown. The objective of this documentary research is to provide information on how metabolites such as phytoestrogens, L-mimosine, labdane diterpenoids - isocupressic acid, quinolizidine alkaloids and piperidine swainsonine, anabasine, coniine and associated alkaloids, among others, exert their action in the animal organism and the effects they produce.

Swainsonine inhibits autophagic degradation and causes cytotoxicity by reducing CTSD O-GlcNAcylation

Swainsonine (SW) is the primary toxin in locoweed, a poisonous plant. SW can cause animal poisoning, affect the quality and safety of meat products and threaten human health, but the mechanism of its toxicity is little defined. Here, we identified 159 differentially expressed proteins, many of which are involved in autophagy and glycosylation modification processes, using proteomics sequencing analysis. O-linked-N-acetylglucosamylation (O-GlcNAcylation) is a glycosylation modification widely involved in various biological processes. Our results show that SW toxicity is related to O-GlcNAcylation. In addition, increased O-GlcNAcylation with the O-GlcNAcase (OGA) inhibitor TMG promoted autophagy, while decreased O-GlcNAcylation with the O-GlcNAc transferase (OGT) inhibitor OSMI inhibited autophagy. Further analysis by Immunoprecipitation (IP) showed that SW could change the O-GlcNAcylation of Cathepsin D (CTSD), reducing the expression of mature CTSD (m-CTSD). In summary, these findings suggest that SW inhibits the O-GlcNAcylation of CTSD, affecting its maturation and leading to the impairment of lysosome function. Consequently, it inhibits autophagy degradation, and causes cytotoxicity, providing a new theoretical basis for SW toxicological mechanism.

Swainsonine promotes apoptosis by impairing lysosomal function and inhibiting autophagic degradation in rat primary renal tubular epithelial cells

Swainsonine (SW), an indolizidine alkaloid, is the primary toxin in locoweeds that causes toxicity syndrome in livestock. Current research shows that SW can induce both apoptosis and autophagy. However, the relationship between, and regulatory mechanism of, autophagy and apoptosis in SW-mediated cytotoxicity remain unclear. In this study, we investigated the role of autophagy and apoptosis in SW-induced cytotoxicity in rat primary renal tubular epithelial cells (RTECs). We examined the effect of SW on lysosomal function using western blotting, transmission electron microscopy, fluorescent microscopy, and flow cytometry. The results showed that SW induced both autophagy and apoptosis, and autophagy protected RTECs from cellular damage. Activating autophagy using rapamycin (Rapa) inhibited apoptosis, while suppressing autophagy using bafilomycin A1 (Baf A1) greatly enhanced SW-induced apoptosis. SW treatment suppressed the expression of lysosomal-related proteins, and co-incubation with SW and aloxistatin (E64d) further promoted apoptosis and LC3-II accumulation in RTECs. These results suggest that SW causes toxicity by disrupting lysosomal dysfunction, inhibiting autophagic degradation, and promoting apoptosis.

Grasslands: A Source of Secondary Metabolites for Livestock Health

The need for environmentally friendly practices in animal husbandry, in conjunction with the reduction of the use of synthetic chemicals, leads us to reconsider our agricultural production systems. In that context, grassland secondary metabolites (GSMs) could offer an alternative way to support to livestock health. In fact, grasslands, especially those with high dicotyledonous plant species, present a large, pharmacologically active reservoir of secondary metabolites (e.g., phenolic compounds, alkaloids, saponins, terpenoids, carotenoids, and quinones). These molecules have activities that could improve or deteriorate health and production. This Review presents the main families of GSMs and uses examples to describe their known impact on animal health in husbandry. Techniques involved for their study are also described. A particular focus is put on anti-oxidant activities of GSMs. In fact, numerous husbandry pathologies, such as inflammation, are linked to oxidative stress and can be managed by a diet rich in anti-oxidants. The different approaches and techniques used to evaluate grassland quality for livestock health highlight the lack of efficient and reliable technics to study the activities of this complex phytococktail. Better knowledge and management of this animal health resource constitute a new multidisciplinary research field and a challenge to maintain and valorize grasslands.

Reproductive Toxicities Caused by Swainsonine from Locoweed in Mice

Swainsonine is the primary toxin in locoweeds. It causes intention tremors, reproductive dysfunction, emaciation, and death. The objective of the present study was to evaluate the potential reproductive and developmental toxicities caused by swainsonine in mice. The treatment groups consisting of three generations of mice were given a range of concentrations of swainsonine by intraperitoneal injection (2.50 mg/kg body weight (BW), 1.20 mg/kg BW, 0.60 mg/kg BW, and 0 mg/kg BW). The 0 mg/kg BW group exhibited significantly fewer estrous cycles and an increased number of estrous ones compared to the 2.50 mg/kg BW, 1.20 mg/kg BW, and 0.60 mg/kg BW groups (P < 0.05). All three generations of mice treated with swainsonine had significantly higher spleen, liver, and kidney indices and significantly lower body weights compared to the 0 mg/kg BW group (P < 0.05). For the first and second generations of treatment group, the copulation indices and the numbers of live pups on postnatal days (PND) 0, 4, and 15 were significantly decreased compared to those of the 0 mg/kg BW group (P < 0.05). The fertility and gestation indices of the treatment group of the first generation were significantly increased compared to the 2.50 mg/kg BW, 1.20 mg/kg BW, and 0.60 mg/kg BW groups of the second generation (P < 0.05). Cumulatively, these results indicate that swainsonine may cause reproductive and developmental toxicities in mice in both parents and offspring.